Communication of tv-anytime crids

ABSTRACT

A method of creating an audio/video stream comprises multiplexing a video component, an audio component, a content reference identifier, and a semantic data packet containing information on the relationship between the video component and the content reference identifier. Apparatus for receiving the audio/video stream, and apparatus for transmitting the audio/video stream are disclosed.

This invention relates to a method of creating an audio/video stream,apparatus for transmitting an audio/video stream, apparatus forreceiving an audio/video stream and to the audio/video stream itself.

Traditionally, the small number of television channels and single methodof delivery (wireless broadcast) meant that an end user could easilytrack the programme schedules to monitor the content delivered to them.However, following the introduction of digital television and theInternet, there has been a rapid increase of the number of channels (nownumbering into the hundreds) and content available to an end user.Equally, the number of delivery methods is has also increased to includebroadcast via fibre optic cable and the old copper wire telephonenetwork. An end user is hard pressed to follow even a small proportionof the content available, with the resulting reduction in enjoyment ofthe available services.

Various interested parties are working on a number of methods ofaddressing this problem. One such group is the TV-Anytime Forum(www.tv-anytime.org) which is developing a system for searching,selecting, locating and acquiring content wherever (i.e. traditionalbroadcasting, Internet-based etc.) or whenever (i.e. scheduled orinstantly accessible) it is made available. In order to realise thisconcept, the Forum has identified three distinct technical areas withrequirements for standardisation, being metadata, content referencingand rights management. These three areas are considered to span theminimum basic features needed to implement a workable end-to-endTV-Anytime system, in which consumers can search for content, makeselections, and acquire content for viewing or capture.

The document TV038r2 (7 Apr. 2000) “Requirements Series: R4 on ContentReferencing Requirements (Normative)” produced by the TV Anytime Forumrefers to various aspects of the content referencing. This document isincorporated by reference herein. The TV Anytime Forum has specified aContent Reference Identifier (CRID) that identifies a specific contentitem, but does not specify where that content item can be found. Howeverthere are problems associated with the content reference identifier andits communication to the end user in a way that is useful for that enduser.

It is therefore an object of the invention to improve the communicationof the content reference identifier.

According to a first aspect of the present invention, there is provideda method of creating an audio/video stream comprising multiplexing avideo component, an audio component, a content reference identifier, anda semantic data packet containing information on the relationshipbetween the video component and the content reference identifier.

According to a second aspect of the present invention, there is providedapparatus for transmitting an audio/video stream comprising amultiplexer for multiplexing a video component, an audio component, acontent reference identifier, and a semantic data packet containinginformation on the relationship between the video component and thecontent reference identifier, and transmitting means for transmittingthe resulting audio/video stream.

According to a third aspect of the present invention, there is providedapparatus for receiving an audio/video stream comprising receiving meansfor receiving an audio/video stream comprising a video component, anaudio component, a content reference identifier, and a semantic datapacket containing information on the relationship between the videocomponent and the content reference identifier and a demultiplexer fordemultiplexing said audio/video stream.

According to a fourth aspect of the present invention, there is providedan audio/video stream comprising a video component, an audio component,a content reference identifier, and a semantic data packet containinginformation on the relationship between the video component and thecontent reference identifier.

Owing to the invention, the end user is supplied with the contentreference identifiers in an easily accessible manner and includingsemantic information on the relationship between the video component andthe content reference identifier. By categorising the various ways inwhich a content reference identifier can be related to the videocomponent and by labelling the semantics of these relationships, theapparatus for receiving an audio/video stream is able to process theidentifier sensibly and is able to construct appropriate user interfacesaccordingly.

Advantageously, the semantic data packet includes information on whetherthe content reference identifier is a current or a linking contentreferencing identifier. The audio/video stream may contain a secondcontent reference identifier, and the semantic data packet containsinformation on both content reference identifiers. Preferably, thesemantic data packet includes information as to whether the or eachcontent reference identifier is time critical.

The apparatus for transmitting the audio/video stream transmits saidaudio/video stream via either a wireless connection (such as a radiolink), or via a wired connection (such as a fibre optic cable). Theapparatus for receiving the audio/video stream is preferably a digitaltelevision receiver. The audio/video stream can be transmitted by anysuitable uni-directional delivery method, including traditionalbroadcast, Internet multicast and one to one file server delivery.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of apparatus for transmitting anaudio/video stream via a cable network to apparatus for receiving anaudio/video stream,

FIG. 2 is a schematic diagram of an audio/video stream,

FIG. 3 is a schematic diagram of a second audio/video stream, and

FIG. 4 is a table of linking content reference identifiers.

In FIG. 1, the apparatus for transmitting the audio/video stream is atransmitter 10 that comprises a multiplexer 12 and transmitting means14. The multiplexer 12 is for multiplexing a video component, an audiocomponent, a content reference identifier and a semantic data packetinto an audio/video stream for transmitting via a suitable deliverynetwork.

The video component and the audio component are shown as supplied to themultiplexer 12 as a single content stream 16, which may be retrievedfrom a database or be generated in real time from, for example, asporting event. Equally, the multiplexer 12 could receive the video andaudio components separately. The content reference identifier and thesemantic data packet are likewise supplied to the multiplexer 12 as asingle data stream 18, although as for the video and audio components,they could be supplied separately.

The semantic data packet contains information on the relationshipbetween the video component and the content reference identifier. Thisis discussed in more detail below. The content reference identifier isunique to content being supplied, and functions as an identifying labelfor that content. The content reference identifier is generatedaccording to a predefined rubric controlled by the content provider.

The audio/video stream comprising the video component, the audiocomponent, the content reference identifier, and the semantic datapacket is transmitted by the transmitting means 14 via a cable network20 to receivers connected to that network 20. Equally, the transmittingmeans 14 could transmit the stream via a wireless connection, such as astandard modulated television signal or satellite broadcast.

One such receiver 22, in the form of a digital television receiver(commonly referred to as a set top box) is shown connected to the cablenetwork 20. This apparatus for receiving an audio/video stream comprisesreceiving means 24 for receiving the audio/video stream and ademultiplexer 26 for demultiplexing the audio/video stream.Additionally, the receiver is provided with standard components such asa CPU, cache memory, main memory etc., not shown for reasons of clarity.

The receiving means 24 of the receiver 22 receives the audio/videostream comprising a video component, an audio component, a contentreference identifier and a semantic data packet and supplies this streamto the demultiplexer 26 which splits the stream into its constituentparts. In normal operation, the demultiplexer 26 supplies the videocomponent to a display device 28, which typically will have audiofunctionality to additionally receive the audio component.

An end user will therefore see displayed on the display device 28 thevideo stream for the channel that they have selected. The cache memoryof the receiver 22 will store the content reference identifier and thesemantic data packet. Using a suitable user interface, such as a remotecontrol, a user can access functions of the receiver 22, usually throughan on screen menu system.

In its simplest use, the content reference identifier will referdirectly to the video stream in which it is embedded, simply being thelabel of that current content. This current content reference identifiercan be used for such things as obtaining enhanced information about thecurrent programme via the user interface. A user can select from an onscreen menu an option to obtain information on the current programme.Once selected, the receiver 22 retrieves the content referenceidentifier from its cache memory and uses this to obtain furtherinformation on the programme, which may be retrieved from an associatedwebsite, or from data delivered by the transmitter 10.

However, in many situations the content reference identifier will notrelate directly to the content being delivered, or there will be morethan one content reference identifier in the audio/video stream. Inthese situations, the functionality of the receiver 22 is greatlyenhanced by it being aware of the relationship between the videocomponent of the audio/video stream and the content reference identifieror identifiers. This is achieved by the presence of the semantic datapacket in the audio/video stream, which contains information on thisrelationship. The CPU is programmed to interpret the semantic datapacket and to adjust the operation of the receiver 22 accordingly.

For example, if a trailer for a forthcoming programme is being shown,then the content reference identifier embedded in the stream will not befor the trailer, but will be for the actual programme being trailered.The semantic data packet will contain information that indicates to thereceiver 22 that the content being delivered is a trailer for a futureprogramme and that the content reference identifier is for the futureprogramme. If the user of the receiver 22 then selects a record functionduring the broadcast of the trailer, the receiver will not record thepresent video and audio components of the audio/video stream. Instead,the receiver 22 will transfer the content reference identifierassociated with the stream from its cache to a buffer in the mainmemory. The receiver 22 can capture the content of the selectedprogramme according to the methodology of the TV Anytime contentreferencing standard.

A number of complicated situations arise when the audio/video streamcontains a second content identifier. In this instance, the semanticdata packet contains information on both content reference identifiers.Should there be more than two identifiers, then the semantic data packetcontains information on all of the content reference identifiers and ontheir relationships to the video component of the audio/video stream.

For example, while a film is being broadcast, the audio/video streamwill include a content reference identifier for the film itself, but mayalso include an identifier for a “making of . . . ” programme that is tobe broadcast soon and may also contain an identifier for the sequel tothe film. The semantic data packet will contain categorising informationon the different content reference identifiers, such that the receiver22 will be able to tell which identifier is which and to render thisinformation in a manner that is useful to the end user. Again taking theexample of recording, if the end user selects the record function, theywill be shown details of the film and of the different programmes linkedto the film and then be able to choose the content that they areactually wish to record.

If the programme being broadcast has a hierarchical structure wherebythe overall programme has smaller constituent parts, in addition to thecontent reference identifier for the overall programme, thesub-divisions will be allocated individual identifiers to allow them tobe recorded in isolation. An example of this is a sports programmecomposed of different sporting events, illustrated in FIG. 2. Thereceiver 22 is able to distinguish between the different hierarchicaltype of identifier based upon the content of the associated semanticdata packet, and therefore to handle the data differently and to presentit to the user in a suitable fashion. Similar situations arise fromprogrammes of “omnibus” and “magazine” format which will have contentreference identifiers for the overall programme and for the differentunits within the programme.

It is also possible that the audio/video stream will contain twodifferent content reference identifiers for two programmes that followeach other. Two programmes adjoining each other may share some commoncontent that the broadcaster considers useful for the receiver 22 tocapture if either of the programmes is recorded, illustrated in FIG. 3.This may be, for example, advertisements, or joining sections. Againthis information is contained in the semantic data packet for processingby the receiver 22.

A combination of the above two scenarios (e.g. two magazine programmesadjoining each other) could lead to four or more identifier contentreference identifiers being transmitted simultaneously. The receiver 22is informed of the type and relationship of each identifier via thesemantic data packet.

In effect, there are two types of content reference identifiers, acurrent and a linking content reference identifier. The semantic datapacket includes information on whether the content reference identifieris a current or a linking content referencing identifier. A currentcontent reference identifier refers directly to the content in which itis embedded, whereas a linking content reference identifier is one thatrefers to another programme, i.e. not the content in which it isembedded. FIG. 4 shows a table of various linking identifiers, andincludes detail in relation to the type of information that would becarried in the semantic data packet. Reference to “AN content” in thisFigure refers to the audio and video content of the audio/video stream.The column headed “Group” refers to whether the content referenceidentifier relates to a group of programmes, or to a single programme.

Certain content reference identifiers are time critical, and thesemantic data packet includes information as to whether the contentreference identifier(s) is (are) time critical. For example, currentcontent reference identifiers are time critical since the receiver 22must start recording at the correct time, whereas a linking identifierthat refers to related programmes is not time critical. The receiver 22processes this information so that it can efficiently identify timecritical content reference identifiers so that action can be taken in atimely fashion.

1. A method of creating an audio/video stream comprising multiplexing avideo component, an audio component, a content reference identifier, anda semantic data packet containing information on the relationshipbetween the video component and the content reference identifier.
 2. Amethod according to claim 1, wherein said semantic data packet includesinformation on whether the content reference identifier is a current ora linking content referencing identifier.
 3. A method according to claim1 or 2, wherein said audio/video stream contains a second contentreference identifier, and the semantic data packet contains informationon both content reference identifiers.
 4. A method according to claim 1,2 or 3, wherein said semantic data packet includes information as towhether the or each content reference identifier is time critical. 5.Apparatus for transmitting an audio/video stream comprising amultiplexer for multiplexing a video component, an audio component, acontent reference identifier, and a semantic data packet containinginformation on the relationship between the video component and thecontent reference identifier, and transmitting means for transmittingthe resulting audio/video stream.
 6. Apparatus according to claim 5,wherein said transmitting means transmits said audio/video stream via awireless connection.
 7. Apparatus according to claim 5, wherein saidtransmitting means transmits said audio/video stream via a wiredconnection.
 8. Apparatus for receiving an audio/video stream comprisingreceiving means for receiving a audio/video stream comprising a videocomponent, an audio component, a content reference identifier, and asemantic data packet containing information on the relationship betweenthe video component and the content reference identifier and ademultiplexer for demultiplexing said audio/video stream.
 9. Apparatusaccording to claim 8, wherein said apparatus is a digital televisionreceiver.
 10. An audio/video stream comprising a video component, anaudio component, a content reference identifier, and a semantic datapacket containing information on the relationship between the videocomponent and the content reference identifier.